This book presents an eye-witness account of the key debates in evolutionary theory over the last thirty years. On one side sit the ultradarwinists, whose ranks include Richard Dawkins, John Maynard Smith and George Williams. On the other side is a more diverse group, the self-styled `naturalists', whose ideas are based on palaeontological studies: here sit Stephen Jay Gould and Niles Eldridge. Although the author's standpoint is avowedly partisan, this book is an important, readable and exciting account of the most significant debate in the life sciences today.